Traditional file system optimizations typically retain the one-to-one mapping of logical files to their physical metadata representations. This rigid mapping results in missed opportunities for an entire class of optimizations in which such coupling is removed.

We have designed, implemented, and evaluated a composite-file file system, which allows many-to-one mappings of files to metadata, and we have explored the design space of different mapping strategies. Under webserver and software development workloads, our empirical evaluation shows up to a 27% performance improvement. This result demonstrates the promise of decoupling files and their metadata.